<?php

/**
 * App_Utf8::to_unicode
 *
 * @author Kohana Team
 * @copyright (c) 2007 Kohana Team
 * @copyright (c) 2005 Harry Fuecks
 * @license http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt
 */
function _to_unicode($str)
{
    $mState = 0; // cached expected number of octets after the current octet until the beginning of the next UTF8 character sequence
    $mUcs4 = 0; // cached Unicode character
    $mBytes = 1; // cached expected number of octets in the current sequence
    $out = array();
    $len = strlen($str);
    for($i = 0; $i < $len; $i ++) {
        $in = ord($str[$i]);
        if ($mState == 0) {
            // When mState is zero we expect either a US-ASCII character or a
            // multi-octet sequence.
            if (0 == (0x80 &$in)) {
                // US-ASCII, pass straight through.
                $out[] = $in;
                $mBytes = 1;
            } elseif (0xC0 == (0xE0 &$in)) {
                // First octet of 2 octet sequence
                $mUcs4 = $in;
                $mUcs4 = ($mUcs4 &0x1F) << 6;
                $mState = 1;
                $mBytes = 2;
            } elseif (0xE0 == (0xF0 &$in)) {
                // First octet of 3 octet sequence
                $mUcs4 = $in;
                $mUcs4 = ($mUcs4 &0x0F) << 12;
                $mState = 2;
                $mBytes = 3;
            } elseif (0xF0 == (0xF8 &$in)) {
                // First octet of 4 octet sequence
                $mUcs4 = $in;
                $mUcs4 = ($mUcs4 &0x07) << 18;
                $mState = 3;
                $mBytes = 4;
            } elseif (0xF8 == (0xFC &$in)) {
                // First octet of 5 octet sequence.
                // This is illegal because the encoded codepoint must be either
                // (a) not the shortest form or
                // (b) outside the Unicode range of 0-0x10FFFF.
                // Rather than trying to resynchronize, we will carry on until the end
                // of the sequence and let the later error handling code catch it.
                $mUcs4 = $in;
                $mUcs4 = ($mUcs4 &0x03) << 24;
                $mState = 4;
                $mBytes = 5;
            } elseif (0xFC == (0xFE &$in)) {
                // First octet of 6 octet sequence, see comments for 5 octet sequence.
                $mUcs4 = $in;
                $mUcs4 = ($mUcs4 &1) << 30;
                $mState = 5;
                $mBytes = 6;
            } else {
                // Current octet is neither in the US-ASCII range nor a legal first octet of a multi-octet sequence.
                trigger_error('utf8::to_unicode: Illegal sequence identifier in UTF-8 at byte ' . $i, E_USER_WARNING);
                return false;
            }
        } else {
            // When mState is non-zero, we expect a continuation of the multi-octet sequence
            if (0x80 == (0xC0 &$in)) {
                // Legal continuation
                $shift = ($mState - 1) * 6;
                $tmp = $in;
                $tmp = ($tmp &0x0000003F) << $shift;
                $mUcs4 |= $tmp;
                // End of the multi-octet sequence. mUcs4 now contains the final Unicode codepoint to be output
                if (0 == -- $mState) {
                    // Check for illegal sequences and codepoints
                    // From Unicode 3.1, non-shortest form is illegal
                    if (((2 == $mBytes) and ($mUcs4 < 0x0080)) or ((3 == $mBytes) and ($mUcs4 < 0x0800)) or ((4 == $mBytes) and ($mUcs4 < 0x10000)) or (4 < $mBytes) or // From Unicode 3.2, surrogate characters are illegal
                    (($mUcs4 &0xFFFFF800) == 0xD800) or // Codepoints outside the Unicode range are illegal
                    ($mUcs4 > 0x10FFFF)) {
                        trigger_error('utf8::to_unicode: Illegal sequence or codepoint in UTF-8 at byte ' . $i, E_USER_WARNING);
                        return false;
                    }
                    if (0xFEFF != $mUcs4) {
                        // BOM is legal but we don't want to output it
                        $out[] = $mUcs4;
                    }
                    // Initialize UTF-8 cache
                    $mState = 0;
                    $mUcs4 = 0;
                    $mBytes = 1;
                }
            } else {
                // ((0xC0 &(*in) != 0x80) AND(mState != 0))
                // Incomplete multi-octet sequence
                trigger_error('utf8::to_unicode: Incomplete multi-octet sequence in UTF-8 at byte ' . $i, E_USER_WARNING);
                return false;
            }
        }
    }
    return $out;
}